Home Forums Hunting & Shooting AR and Tactical Rifles Strength of AR-10 and M1A rifles

I note with do interest loading manuals have service rifle loads for the 223 and 308 and a different set of loads for sporting rifles. Are the AR-10 rifles and M1A's not strong enough for full throttle loads? Like if you ran short of your own and bought a box of whatever at Wallyword are they going to harm the rifle? Curious is all MB

I believe the rifles are strong but the brass isn't. The hotter the load the sooner the actions unlock. If there is too much residual pressure the primer pockets pop or worse yet, the case head bursts.

The action only unlocks early if the gas port is not right... IMHO.

That said I rarely shot warm loads in the AR. Almost nothing but hot. For couple hundred thousand rounds... no ill effects.

M1A I think I shot normal loads though we did run a lot of 185 bergers at 600 which were way better than 168s at the time. Not that the load was hot but the bullet was on the heavy side.

Personally I'd not worry one bit. Certainly not about factory ammo at all. Some military contract stuff has been known to be a bit warm but you'd never get your hands on that stuff.

Overloading it is not right.
You'll notice that when people want to load gasguns like Garands/M-14s over the pressure/pressure curve levels of GI ball, they resort to such things as ported gasplugs. Look at the dedicated 1,000 yard M1As shooting 190+gr bullets.

The same basic thing applies to hot loaded AR15s - people tighten the gas port or add heavier buffers or Tubb carrier weights.

So the gas port is not right for the load. Right?

So, you were repeating my answer?

Bob, read this, especially "Powder and Port Pressure"

http://www.zediker.com/downloads/14_loading.pdf

It's not so much about strength of the action as to what will make them operate dependably. Also, military cases are usually thicker and will develop higher pressures than commercial cases using the same load. But the military cases are preferred because they will last longer.

After you repeated mine? LMAO. Is there an echo in here?

Ah. Glenn. The one that thinks because he has a degree he can make his writing sound so stupid. LOL

AR and Garands run like a helicopter- they operate best when every thing in motion, is in balance.

Change a single factor of the operation (“hot loads”), and the balance is changed, and needs correction from the other direction.

Too heavy of a recoil spring - the load won’t run in either.

Garands - IMHO - are more likely to fail from the battering of the rifle parts in operation, than from a single load. End result is the same, the lugs may crack, or the bolt may crack the receiver if the gas pressure operating the system is higher than it should be.

Either can be made to operate with hotter loads within reason, but you need to be able balance the input through gas, spring, or buffer management.

Jeff can probably make this simpler, but that’s my 2 cents.

Rost, is Zediker off-base in that article? My limited experience with M1A's (compared to yours) made me think he was correct.

Doesn't the M14 have a gas piston/cylinder arrangement that can deal with a wider gas pressure range than the Garand?

Today I am Rost Jr.

M1A is not a Garand

M1 = Garand .30-06

M1A = M14 .308

Yeah - realized I mis-read the OPs question, after I posted - my bad.

I have two M1A', a Squad Scout and a Socom 16. With both came an instruction manual that said both guns were cleared to shoot all commercial and military ammo in good condition. But not the higher velocity stuff like the Federal "High Energy" ammo. The headspace settings, which come with the guns show you that the headspace is set in the overlap range for both types of ammo.
What I've noticed when handloading is that the best accuracy comes with loads that are a couple of grains less than maximum for the heavier cases. I've only loaded with H4895 and TAC powders. E

absolutely correct.
some years ago i acquired a rather limited build m1a. it would not cycle properly. found out eventually it was a spring replacement issue. however, had a gunsmith want to gig me 600bucks for a barrel replacement stating it was out of safe headspace.
took it to a competent gunsmith, and it was set the same as a new springfield so that it could handle commercial .308 or the military 7.62.
I read stuff all the time about how it's safe to hot load, or use commercial ammo in a garand.
i don't like the idea of beating my collection up, and try to keep stuff at the original specs for reloading.
one thing i have dealt with is in loading for m1'a rifles, i have had to use a die that squeezes them in a little more. I also segregate military brass from commercial ajusting the powder load accordingly.

With my M1A loaded and my Socom 16, I only shoot milsurp 7.62x51. Well mostly. I did do some hog hunting with Federal 150 grain .308 SP, with no ill effects.

FIrst off the M1 Garand and the M14 gas systems were designed to fire 150 gr. FMJ ammo. There were Match loads utilizing 173 gr Match bullets for both. Generally speaking if you start changing things up you are likely to drive your port pressures too high and on the M1 will warp the op rod and M14 wreck the gas system.
Cal..30 M1 Rifle port pressure spec is 8000-12000 psi, Min required to "properly" operate is 6000 psi. The 30.06 Match ammo with 173 gr bullets were loaded with IMR 4895 and had 46 gr.in them. I find it shoots much tighter with 43.3 grains.

M1As if you run 40 gr IMR 4895 you should have not problems with 173 gr bullets or lighter.

As mentioned above the military cases are made much heavier than commercial due to the fact the chamber of a semi auto is different than a bolt rifle and the case head is not supported the same in semi autos. Also the commercial cases are lighter and the brass is not as durable as military cases.

CIP I have loaded one LC 1965 Match 30.06 case 157 times and primer pocket is still tight. On commercial ammo you will find the primer pockets will start opening up on as little is 3rd loading.

Military and Commercial chambers are large and brass moves upwards of .007" on firing. For longest case life you don't want brass to move over .002" anywhere when it is fired.

If you properly care for your cases and keep the load pressures on low side your brass will last longer.

Bottom line is if you just go out and buy 308/30.06 it may fire fine but for longest rifle life you need to keep the pressures in the same range the weapon was designed to handle.

Now that being said the military teams did interesting things like drilling small holes in gas port plugs to bleed off the higher pressures generated.

The M1 was converted to 7.62 on a large number of Navy rifles and worked fine. On their match rifles using 30.06 match they issued three op rods with each rifle at start of season and when the groups opened up they changed op rods. When they went to 7.62 the found the same op rod lasted the entire shootinig season as the port pressures from 7.62 were much lower than 30.06.

Be advised ball propellants have a reputation for rapid barrel erosion.

Both the M1 and M1A will shoot much better after their being accurized. Acceptance groups for new M1s was 5" at 100 yards. For M14 it was 5.5" at 100. For the M16 acceptance is 4.5" at 100 yards. All with ball ammo.

The military used throat erosion gages and generally pulled the barrels off when throats wore to the 5th ring. On 30 cal bores the throats ten to move forward .100" per 1000 rounds of spec ammo.

On the AR10 you will probably notice the muzzle blast is much louder and the military match shooters did exotic things like add lead blocks in bottom of mags to make them heaver and easier to control. I knew one shooter than opened his shooting glove and put a 1/4" thick piece of lead in back of glove for more weight.

Of the two M1A's I have the Squad Scout and the Socom 16, neither have been accurized. What I've found is quality ammo make a huge difference in accuracy. The Squad scout with a 1.5-4X scope shoots under 2 inches at 100 yds. for four rounds w/ Federal 168 gr. match. With a handload consisting of 46.3 grs. of TAC, 125 gr. Sierra Pro Hunter Bullet, and new PPU brass, it regularly puts 4 into one inch @ 100 yds. But surplus ammo is a real crap shoot. The worst I've seen is the IMI ammo offered by Midway USA. About 5 inches @ 100 for four rounds. Heck, the 1980 lots of mil surp from England shoot under 3 MOA @ 100 for four rounds. The difference is in the wide range of bullet weights, like plus or minus almost three grains, not .3 grain, and the wide variations in powder charges. E